JPS6265795A - Treatment of high concentration waste water - Google Patents

Abstract

PURPOSE:To make the entire part of a system compact by immobilizing activated sludge only to the denitrifying tank, keeping the activated sludge suspended in a nitrifying tank, applying a membrane sepn. by which nitrifying bacteria, etc. can be separated and recovered for a solid-liquid separator and circulating the separated and recoverd liquid to the nitrifying tank. CONSTITUTION:The high-concn. waste water 1 contg. org. materials and nitrogen at a high concn. (e.g., cattle dung) is passed through a bioreactor 2 packed therein with the moldings immobilized with the activated sludge contg. the denitrifying bacteria and is thereby treated. The liquid is then passed through a bioreactor 3 which has a high-performance aerator 9 and suspends the activated sludge contg. BOD oxidizing bacteria and nitrifying bacteria by the supply of an oxygen-contg. gas. The liquid is thereby treated. The treated liquid is introduced into a membrane separator 4 where the liquid is subjected to a separating and thickening treatment. The separated and concn. liquid obtd. in such a manner is circulated to the reactor 3 and the separated dilute liquid to the reactor 2, respectively. The treated liquid is discharged from the reactor 3. As a result, the microorganism concn. in the bioreactor is increased and the higher treatment in the subsequent stages is simplified by applying the compact device 4.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for treating high-concentration wastewater, that is, a method for treating wastewater containing high concentrations of organic matter and nitrogen, such as human waste, household manure, and fishery processing wastewater, without dilution or in excess of Concerning a method of processing at low dilution.

[Conventional technology]

The conventional method is shown in Figure 2. The high concentration waste liquid 1 and the circulating liquid 5 that circulates from the subsequent process are introduced into a denitrification tank 2, and the oxidized nitrogen (No, -N, NOx-N) contained in the circulating liquid 5 is removed from the waste liquid 1. organic matter is reduced and removed as a carbon source. This denitrification tank 2 mixture is then introduced into a nitrification tank 5 equipped with a high-performance aeration device 9 and supplied with an oxygen-containing gas 10 to oxidize the organic and ammonia nitrogen in the stock solution 1 and convert it into oxidized nitrogen. do. A part of this nitrification mixture is circulated to the denitrification tank 2 as the circulating liquid 5 as described above, and the rest is circulated to the solid-liquid separator 4 (centrifugal concentration and pressure flotation 98 are also available, but gravity concentration is mainly used) The sludge is separated into a separated liquid 8 and a concentrated sludge, and a portion of the concentrated sludge is circulated to the denitrification tank 2 as return sludge 6, and a portion is withdrawn as surplus sludge 7.

[Problem that the invention seeks to solve]

In the above conventional method, plant equipment capacity t7) reduction
In order to reduce the amount of sludge (hereinafter referred to as condensation), it is essential to increase the sludge concentration (bacterial cell concentration) in the biological reaction system, but the following points pose a bottleneck.

(I) Gravity concentration is carried out in a sedimentation tank, but the scale of the facility is extremely large because the separation rate is low. In addition, the separation function is unstable due to qualitative changes in the activated sludge, and nitrifying bacteria are likely to be washed out, which is inconvenient in increasing the bacterial concentration in the biological reaction system. Centrifugal loss condensation and pressurized flotation concentration require smaller facilities than sedimentation tanks, but their solid-liquid separation capabilities are poor and unstable, and the problems with the latter are the same as with gravity concentration.

(2) Based on the above idea, as a method to omit the solid-liquid separation device itself and increase the concentration of microorganisms in a biological reaction system, one of the new technologies in recent years is to immobilize bacterial cells on some kind of carrier and fill it into a biological reaction tank. Bioreactor technology is progressing, and its application in the field of wastewater treatment is highly conceivable. Immobilization methods include carrier binding method (adhering and adsorbing activated sludge to porous materials such as activated carbon, sand, etc.) and entrapping immobilization method using polymer gel (using calcium alginate as a polymer gel). Various methods have been attempted, including a method of sealing activated sludge in the network or lattice structure of these polymeric organic substances using carrageenan, polyacrylamide, etc. A process as shown in FIG. 3 can be considered as a process that improves the conventional method by applying such a method. The symbols in FIG. 3 have the same meanings as in FIG. 2. The activated sludge in the denitrification tank 2 and nitrification tank 3 is not suspended but is immobilized and filled into the tank as an immobilization carrier 11. However, this method has the following problems.

That is, in the nitrification tank 3, a high oxygen dissolution rate is required as a necessary condition for the reaction (that is, it is necessary to supply oxygen to the activated sludge), but the nitrification tank sludge is immobilized as described above. However, the network structure and lattice structure of the carrier becomes an obstacle (that is, it becomes a steric hindrance), increasing the material flow resistance, resulting in high volume load (a large amount of pollutant load with a small equipment capacity), and high sludge. It becomes impossible to keep up with the increase in the required oxygen dissolution rate as the concentration decreases (this becomes an obstacle to reducing the nitrification tank volume). Therefore, it is conceivable to leave the activated sludge in a suspended state (not immobilized) in the nitrification tank, but a solid-liquid separation (bacterial cell separation) device is required, and this is shown in Figure 2. However, there is a risk of washing out the nitrifying bacteria, so even if a solid-liquid separation device is attached, these conventional solid-liquid separation methods cannot be applied as they are.

The present invention proposes a technique for simultaneously solving the above problems; x) and 12).

[Means for solving problems]

The city's invention is a method for treating high-concentration wastewater containing organic matter and nitrogen in highly concentrated or diluted forms with no dilution or ultra-low dilution. The liquid is passed through the bioreactor (I) filled with the molded product, and then the BOD is equipped with a high-performance aeration device.
Bioreactor (II) K that suspends activated sludge containing oxidizing bacteria and nitrifying bacteria by supplying oxygen-containing gas
The treated liquid is then introduced into a membrane separation device for separation and concentration, and the resulting separated concentrated liquid is transferred to the bioreactor (I1) and the separated diluted liquid is transferred to the bioreactor (+). The present invention relates to a high-concentration wastewater treatment method characterized by circulating and extracting a treated liquid from a bioreactor (II).

That is, in the present invention, activated sludge is immobilized only in the denitrification tank 2 [bioreactor (I) of the present invention], and in the nitrification tank 3 [bioreactor (■) of the present invention], compared to the conventional Figures 2 and 3. ] The activated sludge is not immobilized but remains in a floating suspension state, and the solid-liquid separator 4 uses membrane separation that can highly separate and recover microbial cells such as nitrifying bacteria, and the separated and recovered liquid is sent to the nitrification tank 3. By circulating the boat, the above points (I) and r2) are resolved.

Note that various conventional methods (such as comprehensive immobilization method) can be applied to immobilize activated sludge in the denitrification tank 2, that is, the Bio IJ 7 tank (I) of the present invention.

Also, those that can be applied to the membrane separation of the solid-liquid separator 4 include ultrafiltration membranes using synthetic polymer membranes such as polyacrylonitrile membranes.

[Effect]

By immobilizing the activated sludge in the denitrification tank [bioreactor (I)], the concentration of microorganisms in the tank is improved.

Nitrification requires oxygen supply! The activated sludge in '1m [bioreactor (■)] is kept in a floating suspension state to avoid inhibition of oxygen supply, which is a drawback of immobilization of activated sludge.

As a means of separating nitrified sludge, a membrane separation device using an ultrafiltration membrane or the like is used to almost completely prevent leakage and washing out of nitrifying bacteria, etc., and to improve the concentration of organisms inside the tank [bioreactor (II)] (eliminating obstacles to concentration improvement). Further, by using this membrane separation device, a treated liquid of high quality water can be obtained, and the advanced treatment after the present invention can be simplified.

The separated concentrated liquid obtained by the membrane separation device is activated sludge such as nitrifying bacteria that has flowed out from the bioreactor (II). By circulating the vaginal fluid to the bioreactor (II), the activated sludge is transferred to the bioreactor (II). II). Since the activated sludge in the bioreactor (I) is fixed, there is no need to recover it.

In addition, by circulating the separated dilute solution obtained by the membrane separation device to the bioreactor (I), the bioreactor (
NOx4 generated by oxidizing NH4-N in II) becomes N
It is returned to a goose.

〔Example〕

An embodiment of the method of the present invention will be explained based on FIG. The high concentration waste liquid 1 is first transferred to the denitrification tank [bioreactor (I)].
) 2 and the nitrification tank [Bioreactor (II)
) Nox-N (No2-N, No3-
N) is reduced and removed using the organic matter in the waste liquid 1 as a carbon source.

At this time, in the bioreactor (I) 2, the activated sludge is immobilized using some kind of usual carrier and filled into the tank.

Various methods can be used to immobilize this activated sludge, including the method using a gel of a polymeric organic material such as calcium alginate, K-carrageenan, or polyacrylamide as described above. The denitrification tank mixture is further introduced into a bioreactor (marked 3), where it is heated to an oxygen-containing gas 10 by a high-performance aeration device 9.
However, in the bioreactor (■) 5, the activated sludge is in a floating suspension state. After that, for example, in the membrane separation device 4 using an ultrafiltration membrane, for example, the liquid pressure 2 to 3 a
A high degree of bacterial cell separation is carried out in tm, and a part of the separated concentrated liquid is circulated from line 6 to the bioreactor (auxiliary 3), and the separated diluted liquid is circulated as the above-mentioned circulating liquid 5 to the bioreactor (I). The liquid treated in the bioreactor (■) 3 is extracted from the system as a dilute separated liquid 8 through the membrane separation device 4.

〔Effect of the invention〕

The concentration of microorganisms in the biological reaction tank can be significantly increased, and by using a compact membrane separation device, the conventional large-capacity sedimentation tank can be omitted, and the subsequent advanced treatment can be simplified. The entire system can be made significantly more compact.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, and FIGS. 2 and 3 show a conventional method. Sub-Agents 1) Meifuku Agent Ryo Hagiwara − Sub-Agent Atsuo Anzai

Claims (1)

[Claims] In a method for treating highly concentrated waste liquid containing high concentrations of organic matter and nitrogen with no dilution or ultra-low dilution, the high concentration waste liquid is first filled with a molded product in which activated sludge containing denitrifying bacteria is immobilized. Next, the activated sludge containing BOD oxidizing bacteria and nitrifying bacteria is suspended in a bioreactor equipped with a high-performance aeration device by supplying oxygen-containing gas. (II), and then introduce this treated liquid into a membrane separator for separation and
Concentration treatment is performed, and the resulting separated concentrate is transferred to a bioreactor (
II), a highly concentrated wastewater treatment method characterized by circulating the separated diluted solution through the bioreactor (I) and extracting the treated solution from the bioreactor (II).